Turbine blades



Feb. 14, 1967 AKIO SOHMA 3,304,056

TURBINE BLADES Filed Nov. 16. 1965 INVENTOR 4/00 309/14 ATTORNEY UnitedStates Patent 3,304,056 TURBINE BLADES Akio Sohma, Hitachi-shi, Japan,assignor to Hitachi, Ltd., Tokyo, Japan, a corporation of Japan FiledNov. 16, 1965, Ser. No. 508,116 Claims priority, application Japan, Mar.19, 1965, ill/15,659 6 Claims. (Cl. 253-76) The present inventionrelates to turbine blades and more particularly to turbine blades whichare operable at the low pressure stage of a turbine or in the wet steamregion of a turbine for the nuclear reactors and for the generation ofsubterranean heat.

In the turbine blades operable in the aforesaid wet steam region ofturbines it has been more effective to eliminate water drops containedin the wet steam in order to raise the efiiciency of the turbine bladesand to prevent erosion of parts inside the turbine, particularly of thetips of turbine blades running with great peripheral speed, and therebyto prolong the life of the blades. A variety of methods has heretoforebeen contemplated in order to remove said water drops to avoid theerosion of the blades. However, the object was not attained due todifiiculties that the moisture in the steam and the revolution of theblades urged the speed of water drops to collide with the surfaces ofthe blades as the moisture gradually increased and the revolution wasaccelerated.

One example of the construction of turbine blades which have beenadopted conventionally for the separating of the water drops adhering onthe turbine blades comprised the provision of a plurality of separationgrooves cut on a turbine blade for guiding and discharging the waterdrops into the peripheral chamber around the turbine blade. Theconstruction of the turbine blade of this type was well adapted forguiding the water drops to the tips of the blades and to discharge andseparate them from the surfaces of the blades but it has accompanieddangers to deform the grooves by erosion caused from the effect of thewater drops, with the result that the separation of the water drops wasnot accomplished satisfactorily and the safety of the turbines wasgreatly injured.

Another attempt to avoid the erosion of the turbine blades was to applya stellite plate on a part of blade which is mostly exposed to the waterdrops. Such stellite plate was surely capable of reducing the erosion ofthe surfaces of the turbine blades on account of high resistivity of thestellite material against erosion but could not effectively achieve theseparation and removal of the water drops from the turbine blades.

Thus it has become very important to prevent the erosion of the turbineblades for operating in the wet steam region, and with this in view itis now proposed to provide a means for discharging the water drops fromthe turbine blades as promptly as possible so that the erosion may nottake place on the turbine blades due to water drops and for increasingthe safety of the turbine blades endurable to operate for many hours.

The construction of the turbine blades as proposed according to thisinvention will more clearly be apparent from the following descriptionwhen read in conjunction with the accompanying drawing, in which:

FIGURE 1 is a perspective view of the stellite plate provided withgrooves according to this invention;

FIGURE 2 is a plan view of the turbine blade provided with the stelliteplate having the grooves as shown in FIGURE 1;

FIGURE 3 is a front view of the stellite plate having the grooves asshown in FIGURE 1;

FIGURE 4 is a perspective view of the turbine blades ice I stelliteplate 1 on the surface of a turbine blade 2 in a predetermined regionwhere the water drops mostly collide. The stellite plate 1 as shown inFIG. 1, is provided with guide grooves to allow the separation of waterdrops to continue at all times. In the region 4 at the tip of theturbine blade against which the water drops mostly strike there isprovided a recess 6 to receive the stellite plate 1 as shown in FIGS. 2and 3. The stellite plate 1 is adapted to fit into the recess 6 andfixed by soldering in the manner that no troubles will occur and hamperthe operation of the turbine. The guide grooves 3 for separating thewater drops are shaped so as to make the Water drops separate toward thedirection of the tips of the turbine blades.

FIG. 4 shows an embodiment of the turbine blades thus assembled in anentirety.

According to the same embodiment shown by FIG. 5, it may well beappreciated that the water drops coming into contact with or strikingagainst the turbine blade gather into the grooves on the turbine bladeand flow along the grooves by centrifugal force of the turbine blades.Thereafter such water drops are led to the tips of the turbine bladesand discharged therefrom into the peripheral chamber 7 and removed outof the turbine casing.

For maintaining the separation of water drops as desired and theresistivity of the stellite plate against erosion the present inventionhas employed a stellite plate of Co'Cr-W alloy material. Such stelliteplate, however, can be substituted for other erosion resistant alloymaterial to serve the same purpose, therefore the application ofmaterial may not be restricted only to the aforesaid alloy metal if itdoes not depart from the spirit and scope of the present invention andthe claims.

It should be noted further that a plate of the same material as theturbine blade can likewise be employed instead of a stellite plate andis fitted into the recess in the same manner as described above. Inother cases such plate can be replaced with other similar plate bysimply removing the soldering after it has been heavily eroded. Thestellite plate also can be replaced with other stellite plate byremoving the soldering.

By the use of the turbine blades of the present invention having aconstruction as described above, not only is it possible to preventerosion or deformation of the turbine blades even during operation for aprolonged period, but it is also possible to operate the turbine blaleswithout reduction in water drop separating efficiency.

What I claim is:

1. A turbine blade including an erosion resistant alloy plate having aplurality of generally parallel grooves and being rigidly attached byfusion to the upstream end radially outward portion of the turbine bladeso that the grooves extend in the radial direction of the turbine blade.

2. The turbine blade of claim 1, wherein said plate is constructed of astellite cobalt-chromium-tungsten alloy.

3. An elastic fluid turbine, comprising: a rotor having a plurality ofgenerally radially extending contoured turbine blades; each of saidblades having an elongated recess extending generally radially along theback of said "blade; a plate of relatively high erosion resistantmaterial having the general shape of said recess and being rigidlyattached within in each of said recesses; said 3 plate having aplurality of closely spaced, generally parallel grooves on its back faceextending generally in the radial direction; a relatively stationaryturbine casing surrounding said rotor and having means for collectingand removing condensation that has been collected in said grooves; movedradially outward by centrifugal force along said grooves, and dischargedradially from said grooves.

4. The fluid turbine according to claim 3, wherein each of said recessesopen in the upstream and radial outward directions, each of saidrecesses extend from the tip of said blade along the major radialdimension of said blade to a point substantially spaced from the root ofsaid blade and from the upstream edge of said blade for only a minorportion of the axial dimension of said blade, said grooves extend forthe full radial dimension of each of said plates, and said platecompletely fills said recess.

5. The turbine according to claim 4, wherein said plate is constructedof a cobalt-tungsten-chromium stellite alloy.

6. The turbine according to claim 3, wherein said plate is constructedof a cobalt-tungsten-chromium stellite alloy.

References Cited by the Examiner UNITED STATES PATENTS 1,829,674 10/1931 Rosenlocher 25376 1,862,827 6/1932 Parsons et al. 25377 3,215,51111/1965 Chisholm et al.

FOREIGN PATENTS 360,230 11/ 1931 Great Britain. 619,722 3/ 1949 GreatBritain OTHER REFERENCES Knowlton, abstract of application Serial No.133,199, published June 5, 1951.

m MARTIN P, SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, JR., Examiner.

1. A TURBINE BLADE INCLUDING AN EROSION RESISTANT ALLOY PLATE HAVING APLURALITY OF GENERALLY PARALLEL GROOVES AND BEING RIGIDLY ATTACHED BYFUSION TO THE UPSTREAM END RADIALLY OUTWARD PORTION OF THE TURBINE BLADESO THAT THE GROOVES EXTEND IN THE RADIAL DIRECTION OF THE TURBINE BLADE.